This background description is set forth below for the purpose of providing context only. Therefore, any aspects of this background description, to the extent that it does not otherwise qualify as prior art, is neither expressly nor impliedly admitted as prior art against the instant disclosure.
As more customers in the aircraft industry require extended maintenance service intervals, manufacturers and suppliers have been converting many sealing applications to hydrodynamic sealing technology. Historically, standard service intervals were roughly 10,000 hours. However, some recent requirements have been as high as 40,000 hours, or more. Higher service intervals typically require sealing reliability to be significantly increased, which has led to increasing interest in hydrodynamic sealing technology.
Hydrodynamic seals generally include a seal assembly or face seal, and a rotor or mating ring. The seal components operate on a hydrodynamic air film during normal operation and generally operate in the contact mode only during start-up and shutdown. To be effective, hydrodynamic seals typically involve precise control of the sealing surfaces—i.e., a seal face on a face seal and on a mating ring.
Mating rings are often attached to a shaft, which is a rotating element. It is common design practice to allow for a slip fit between the mating ring and rotating shaft. The mating ring may be positioned in such a way that the clamping load is applied through the adjacent components and into the mating ring. The surfaces on adjacent components can influence the sealing surface of the mating ring. These adjacent component surfaces, commonly referred to as interface control surfaces, are generally controlled through tolerancing or geometric features.
In assemblies in which a clamping nut is an adjacent component providing clamping force or load against a mating ring, the sealing surface of the mating ring may become distorted, since the primary guide of the clamping nut will be the threads of the clamping nut. However, in instances, the threads on the clamping nut may not provide a sufficient precision guide for applying a desired clamping load to a corresponding mating ring.
With the design of a hydrodynamic mating ring and assembly, a great deal of analysis may be involved to better ensure the appropriate coning of the sealing surface once the hydrodynamic mating ring is installed. The analysis can involve a number of assumptions as to the coning value, particularly in instances in which a clamping nut is in direct contact with a hydrodynamic rotor. With such instances, the coning values may vary greatly.
There is therefore a desire for solutions/options that better control clamping surfaces or interfaces, and/or minimize or eliminate one or more of the above-described challenges. The foregoing discussion is intended only to illustrate the present field and should not be taken as a disavowal of scope.